System and method of controlling the demarcation line formed on partially electroplated articles

ABSTRACT

A processing system, electroplating cell, and method of reducing the ration (i.e., demarcation line) that often forms on articles undergoing a partial plating process. The processing system may include a loading station, pre-processing station, electroplating station, post-processing station, unloading station, and a transport system that transports the articles to the various stations. The electroplating cell comprises a container to support a plating fluid bath, an anode electrode, a support structure, which may be part of the transport system, to support the articles such that only a portion thereof is immersed in the plating fluid bath and an air flow system adapted to cause air flow proximate the interface of the articles to the plating fluid bath. The air flow near the articles prevents or reduces plating fluid vapors from impinging the articles, thereby reducing the discoloration that would otherwise form on the articles.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of ProvisionalPatent Application Ser. No. ______, filed on Mar. 30, 2005, and entitled“System and Method of Electroplating Relatively Small Articles,” whichis incorporated herein by reference. This application is also related toPatent Application, Ser. No. ______, filed on ______, and entitled“System and Method of Transporting and Providing a Cathode Contact toArticles in an Electroplating System,” which is incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates generally to electroplating systems, and inparticular, to a system and method of controlling the demarcation lineformed on a partially electroplated article.

BACKGROUND OF THE INVENTION

The electroplating of relatively small articles, such as connector pinsand sockets, presents many challenges. These challenges includeproviding a relatively uniform metallic coating on the articles,efficiently using the amount of plating solution to plate the articles,and configuring the plating process and equipment to electroplate largequantities of relatively small articles, while maintaining platinguniformity and consistency.

There are presently many techniques for electroplating small articles.One such technique is referred to in the relevant field as “barrelplating.” In barrel plating, small articles are placed into a barrelcontaining plating solution and an internal lose wire, typicallyreferred to as a “dangler”, to act as an anode. The barrel is typicallypositioned on its side and continuously rotated while a plating currentis formed through the plating solution. A drawback of the barrel platingtechnique is that the entire surface of each of the articles is plated.If the entire surface need not be plated, the barrel plating techniqueresults in a substantial excess of plating, which can be very expensiveover many runs and time.

In the case where the entire surface of an article need not be plated,only the particular surface of the article that requires plating isimmersed in the plating solution while undergoing an electroplatingprocess. Such partial plating technique requires many considerations,including consistency in the amount of surface plated fromarticle-to-article, consistency in the uniformity of the plating formedon the partial surface of the articles, and control of the demarcationlines typically formed on the articles. These considerations are furtherexplained with reference to the following example.

FIG. 1 illustrates a side view of a relatively small article 100undergoing an electroplating process wherein only a portion of itsentire surface is being plated. In this example, the article 100 may bea contact pin or socket. The article 100 is supported in a verticalorientation by a belt 102. In particular, the article 100 includes awider head portion that rests on the belt 102, and a narrow body portionthat extend below the belt 102 through an opening thereof. The lowerportion of the article 100 is immersed in plating solution 108. An anode106 is also immersed in the plating solution, and in this example, issituated directly below the article 100. The cathode makes electricalcontact to the head portion of the article 100. If the article 100 is asocket, it may include a cavity 104 with an opening situated coaxiallyat the lower portion of the article 100.

As discussed above, the electroplating of relatively small articlesrequires many considerations. For instance, there is the considerationof the consistency in the amount of surface plated fromarticle-to-article. In this example, it is desired that the lowerportion of the article 100 be plated to a height of H±ΔH, where ΔH is anacceptable error for the height H. If the electroplating process isunable to achieve the height requirement on a consistentarticle-to-article basis, many articles will be defective which candrive up substantially the costs of plating the articles. Thus, in orderto provide consistency in the amount of surface plated fromarticle-to-article, the height of the plating fluid and the verticalposition of the article 100 should be well controlled.

Also, as discussed above, another consideration in providing desirableelectroplating of relatively small articles is the uniformity of theplating formed on the partial surface of the articles. In this example,if the article 100 is a socket, it would be desirable to uniformly platethe cavity 104 of the socket because that is the region where electricalcontact to the socket would normally be made. Accordingly, positioningthe anode 106 directly below the article 100 optimizes the plating ofthe cavity 104 since the electric field (shown as arrows with dashedlines) has generally a preferred path to the cavity 104.

However, if the article is a pin, it would be more desirable to focusthe plating to the outer wall of the pin; the region where electricalcontact to the pin would normally be made. In this case, the positioningof the anode 106 directly below the article 100 does not optimize theplating of its outer wall since the electric field does not have agenerally preferred path to the outer wall. In such a case, it would bepreferable to place the anode 106 on the side of the pin. However, thepositioning of the anode 106 to the side of the pin, would not bedesirable for plating a socket. Thus, to provide optimal plating ofdifferent articles (e.g., sockets, pins, etc.), it would be desirablefor the position of the anode relative to the article to be adjustable.

Further, as discussed above, the other consideration in providingdesirable electroplating of relatively small articles is the control ofthe demarcation line formed on the articles. Often, during the partialplating of an article 100, a discoloration 110, often referred to as ademarcation line, forms on the article 100 near the surface of theplating solution. It has been previously theorized that the demarcationline 110 was formed by the surface of the plating solution. Throughvarious experiments, it has been discovered by the inventors that thedemarcation line 110 actually forms on the article 110 a relativelyshort distance above the surface of the plating solution. The inventorstheorized that the demarcation line 110 is formed by ejection of theplating fluid and subsequent impingement of the plating fluid vaporsonto the article. Based on this theory, the inventors have devised asystem and method of preventing or reducing the occurrence of theformation of the demarcation line 110 on articles.

Also, in an electroplating system, the articles are typicallytransported from a loading station through various processing stations,and then to an unloading station. When the articles are within theelectroplating station, a cathode contact to the articles is needed toperform the electroplating process. Accordingly, there is a need for atransport system that not only transports the articles from the loadingstation to the unloading station by way of the various processingstations, but there is a further need for the transport system toprovide a cathode contact to the articles.

These needs and other are met by the various exemplary embodiments ofthe invention described in detail below.

SUMMARY OF THE INVENTION

An aspect of the invention relates to a processing system,electroplating cell, and method of electroplating only a desired portionof respective articles. The processing system comprises a pre-processingstation including one or more cells to perform one or morepre-electroplating processes on the articles, for example an activationand rinse processes; an electroplating station including one or morecells to plate the articles with one or more desired materials, forexample gold; and a post-processing station including one or more cellsto perform one or more post-electroplating processes, for example, adragout rinse, hot deionized rinse, and hot air dryer processes. Theprocessing system may further include a transport system to transportthe articles from a loading station to an unloading station by way ofthe pre-processing, electroplating, and post-processing stations.

The electroplating cell comprises a container to support a plating fluidbath and an anode electrode situated within the container and adapted tocontact the plating fluid bath. The methodology of electroplating only adesired portion of the respective articles entails several aspects suchas the transport system being secured to a fixed member such that thevertical position (i.e., height) of the articles remains substantiallyconstant as the articles are transported in and out of theelectroplating cell. Also, the electroplating cell includes avertical-adjustment mechanism to adjust the height of the container suchthat the desired portion of the respective articles is immersed in theplating fluid bath at a precise controlled depth. The electroplatingcell further includes a flow control system to control the flow rate ofplating fluid into the container such that the height of the surface ofthe plating fluid bath is maintained substantially constant. Thecontainer additionally includes one or more bleed holes through itswalls, which assist in stabilizing the surface of the plating fluidbath.

Another aspect of the invention relates to a processing system,electroplating cell, and method of adjusting the effective position of aplurality of anode electrodes to desirably electroplate different typearticles. The processing system may be similar to the one describedabove, including a loading station, pre-processing station,electroplating station, post-processing station, unloading station, anda transport system that transports the articles to the various stations.The electroplating cell comprises a container to support a plating fluidbath, a plurality of spaced-apart anode electrodes situated within thecontainer and adapted to contact the plating fluid bath, and a powersupply system adapted to energize a first subset of the anode electrodeswith an anode voltage when plating one or more first type articles, andto energize a second and different subset of the anode electrodes withan anode voltage when plating one or more second and different typearticles.

Another aspect of the invention relates to a processing system,electroplating cell, and method of reducing the discoloration (i.e.,demarcation line) that often forms on articles undergoing a partialplating process. The processing system may be similar to the onesdescribed above, including a loading station, pre-processing station,electroplating station, post-processing station, unloading station, anda transport system that transports the articles to the various stations.The electroplating cell comprises a container to support a plating fluidbath, an anode electrode situated within the container and adapted tocontact the plating fluid bath, a support structure, which may be partof the transport system, to support the articles such that only aportion thereof is immersed in the plating fluid bath, and a gas flowsystem adapted to cause gas flow (e.g., air, nitrogen gas, argon gas,etc.) proximate the interface of the articles to the plating fluid bath.The gas flow near the articles prevents or reduces plating fluid vaporsfrom impinging the articles, thereby reducing the discoloration thatwould otherwise form on the articles.

Another aspect of the invention relates to a processing system,transport subsystem, cathode contact subsystem and method of providing acathode contact to the articles being transported within anelectroplating cell. The processing system may be similar to the onesdescribed above, including a loading station, pre-processing station,electroplating station, post-processing station, unloading station, anda transport system that transports the articles to the various stations.The transport system comprises an electrically conductive, movablesupport structure to support the articles; and the cathode contactsystem is adapted to provide a cathode potential to the one or morearticles by way of the electrically conductive, movable supportstructure.

Another aspect of the invention relates to a processing system,electroplating cell, transport system, cathode contact subsystem andmethod of providing a cathode contact to the articles being transportedwithin an electroplating cell. The processing system may be similar tothe ones described above, including a loading station, pre-processingstation, electroplating station, post-processing station, unloadingstation, and a transport system that transports the articles to thevarious stations. The electroplating cell comprises a container tosupport a plating fluid bath, and an anode electrode situated within thecontainer and adapted to contact the plating fluid bath. The transportsystem is adapted to transport the articles to and from the variousstations. The cathode contact system comprises anelectrically-conductive moving structure adapted to make cathode contactto said articles and move substantially in synchronous with thearticles.

Another aspect of the invention relates to a processing system,electroplating cell, transport system, cathode contact subsystem andmethod of providing a cathode contact to the articles being transportedwithin an electroplating cell. The processing system may be similar tothe ones described above, including a loading station, pre-processingstation, electroplating station, post-processing station, unloadingstation, and a transport system that transports the articles to thevarious stations. The transport system comprises a plurality of carrierssupported by a conveyor structure. Each of the carriers are adapted tosupport at least one article, but may be able to support a plurality ofarticles configured into various patterns, such as a single row, or aplurality of rows (i.e., an array). Further, the carriers are adapted toprovide a cathode contact to the articles.

Other aspects, features, and techniques of the invention will beapparent to one skilled in the relevant art in view of the followingdetailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of a relatively small article undergoingan electroplating process where only a portion of its entire surface isbeing plated;

FIG. 2 illustrates a side view of an exemplary electroplating system inaccordance with an embodiment of the invention;

FIG. 3 illustrates a side cross-sectional view of an exemplaryelectroplating cell in accordance with another embodiment of theinvention;

FIG. 4 illustrates a block diagram of an exemplary system forcontrolling the plating fluid flow into the electroplating cell inaccordance with another embodiment of the invention;

FIG. 5A illustrates a side view of an exemplary anode electrodeconfiguration operated in a first manner in accordance with anotherembodiment of the invention;

FIG. 5B illustrates a side view of the exemplary anode electrodeconfiguration operated in a second manner in accordance with anotherembodiment of the invention;

FIG. 6 illustrates a block diagram of an exemplary anode power system inaccordance with another embodiment of the invention;

FIG. 7A illustrates a side view of an exemplary cathode contact systemin accordance with another embodiment of the invention;

FIG. 7B illustrates a side view of another exemplary cathode contactsystem in accordance with another embodiment of the invention;

FIG. 8 illustrates a side view of an exemplary cathode contact preloadsystem in accordance with another embodiment of the invention;

FIG. 9A illustrates a side view of the exemplary cathode contact preloadsystem in contact with a pair of articles in accordance with anotherembodiment of the invention;

FIG. 9B illustrates a side view of another exemplary cathode contactpreload system in contact with a pair of articles in accordance withanother embodiment of the invention;

FIG. 10 illustrates a block diagram of an exemplary synchronizationsystem to synchronize the speed of the article transport conveyor beltwith the cathode contact conveyor belt in accordance with anotherembodiment of the invention;

FIG. 11 illustrates a side view of a portion of the exemplary articletransport system in accordance with another embodiment of the invention;

FIG. 12A illustrates a side view of an exemplary carrier in accordancewith another embodiment of the invention;

FIG. 12B illustrates a side view of another exemplary carrier inaccordance with another embodiment of the invention; and

FIGS. 13A-D illustrate front, side, top and open views of anotherexemplary article transport system in accordance with another embodimentof the invention.

DETAILED DESCRIPTION OF THE INVENTION

I. Overall Electroplating System

FIG. 2 illustrates a side view of an exemplary electroplating system 200in accordance with an embodiment of the invention. The electroplatingsystem 200 comprises a loading station 202, a transport system 204, apre-processing station 206, an electroplating station 208, apost-processing station 210, an unloading station 212, and a controlunit 214. The loading station 202 automatically loads articles onto thetransport system 204. The transport system 204 transports the articlesfrom the unloading station 202 through the various processing stations206, 208, and 210, and finally to the unloading station 212.

In this example, the pre-processing station 206 performs an activation(e.g., cleaning) and rinsing of the articles. The electroplating station208 performs one or more electroplating processes to form a desiredplating of the articles. The post-processing station 210 performs adragout rinse, a hot de-ionized (DI) water rinse, and a hot air dryingof the articles. The unloading station 212 unloads the articles from thetransport system 204 into an output bin 244. The control unit 214controls the operations of the electroplating system 200.

More specifically, the loading station 202 comprises a feeder hopper220, a bowl feeder 222, an inline feeder tract 224, and a drop tubeescapement 226. The feeder hopper 220 receives articles to undergo theprocesses provided by the electroplating system 200. In this example,the feeder hopper 220 holds approximately ½ cubic feet of articles to beprocessed, and dispenses articles to the bowl feeder 222 based on asignal it receives therefrom. For example, the feed hopper 220 isdisabled unless it receives a low-level condition signal from the bowlfeeder 222.

The bowl feeder 222 orients the articles appropriately (e.g., in asubstantial vertical fashion with the portion thereof to be platedsituated at the lower end of the articles), and serially provides theoriented articles to the inline feeder tract 224. The inline feedertract 224 transports the articles in a linear fashion to the drop tubeescapement 226. The drop tube escapement 226, using a pressurized airnozzle, releases single articles downward to respective carriersperiodically spaced on a conveyor belt as part of the transport system204. The drop tube escapement 226 releases articles on the basis of aposition encoder which tracks the position of the carriers as theconveyor belt moves and sends signals to the drop tube escapement 226 atthe proper times to cause the articles to be inserted into respectivecarriers.

As is discussed in more detail below, the transport system 204 includesa horizontally-oriented endless conveyor belt rotationally supported byvertically-oriented 371 and 372. As discussed above, the belt is tooledwith removable carriers situated into periodic spaced-apart openingsthrough the belt. In this example, the transport system 204 may includetwo independent conveyor belts each with their own loading and unloadingstations 202 and 212. The belts are, however, attached to a common drivemotor 373 with closed loop speed control. Each conveyor belt has anindependent tensioning and disengaging device to allow the running ofone conveyor belt while the other is available for servicing. It shallbe understood that the belt may be replaced with other types ofconveyable structures, such as a chain or cable.

As discussed above, the pre-processing station 226, in this example,includes an activate cell 230 and a flood rinse cell 232. The processperformed in the activate cell 230 serves to remove contaminants, suchas light surface soils and metal oxides, from the articles prior toplating. In this example, the articles may be immersed in a bath ofalkaline solution. Alternatively, or in addition to, the articles mayundergo an anode and/or cathode cleaning process to generate oxygen(reverse) or hydrogen (direct) on the surface of the articles. In such acase, electrodes are also immersed in the solution to generate thecurrent needed to perform the anode and/or cathode cleaning process.There are many other processes that may be employed in the activate cell230 in order to prepare the articles for the electroplating process.

In the flood rinse cell 232, the articles undergo a process to removeand contain residual activation chemistry (also known as “dragout”) thatmay be present on the surface of the articles due to the prioractivation process. This prevents the activation chemistry fromcontaminating the electroplating cell 234. In this example, the articlesmay be immersed in de-ionized water reservoir and/or sprayed also withde-ionized water. The de-ionized water may be recirculated to and from arinse reservoir. In such a case, the de-ionized water may be replacedwith clean water on a time basis. Accordingly, a programmed timer may beprovided to operate a valve to open a fresh DI water supply line inorder to replenish the rinse reservoir.

As discussed above, the electroplating station 208 may include one ormore plating cells. In this example, two gold electroplating cells 234and 236 are shown. It shall be understood that the electroplating neednot be limited to gold. Other materials may be used to plate thearticles. As discussed in more detail in Section II entitled theElectroplating Station, each of the electroplating cells 234 and 236 areconfigured to control the amount of partial plating of the articles;adjust the effective position of the anode to improve the plating ofselected regions of the articles; reduce or eliminate the demarcationline that would otherwise form on the articles; provide a cathodeconnection to the articles that reduces contamination of theelectroplating cell.

As discussed above, the post-processing station 210, in this example,includes a dragout rinse cell 238, a hot DI rinse cell 240, and a hotair dryer cell 242. In the dragout rinse cell 238, a process may beemployed to remove residual chemistry remaining on the articles due tothe prior electroplating process or processes. The process may besimilar to the one performed in the flood rinse cell 232 previouslydescribed. Additionally, the process may include a gold recovery chamberto collect any gold metal removed from the articles during the rinseprocess. In particular, the gold recovery chamber may include ionexchange resin beads, which attract the gold metal as the recirculatedwater passes through the chamber. After a determined time period, theresin beads are removed from the chamber, and the gold metal isrecovered from the resin material.

In the hot rinse cell 240, a process may be employed to remove anyremaining residues from the articles due to the prior dragout rinseprocess. In this example, the articles are subjected to a rinse (e.g.,bath and/or spray) using hot deionized water, which may also berecirculated. The hot rinse cell 240 may be equipped with a heater toraise the temperature of the water to a desired level.

In the hot air dryer cell 242, a process may be employed tosubstantially dry the articles. In this example, the hot air dryer cell242 includes a metal chamber that encloses that portion of the conveyorbelt and articles thereon. A thermostatically controlled hot air blowermay be located at the bottom of the metal chamber. The chamber may bedesigned to direct a flow of temperature-controlled hot air around thearticles as the conveyor belt passes through the cell 242 tosubstantially remove the residual water from the articles due to theprior hot DI rinse process.

As discussed above, the electroplating system 200 also includes aloading station 212 that removes the processed articles from theconveyor belt and into an output bin 244. In this example, the outputbin 244 is located below the drive wheel of the conveyor belt to collectthe articles as they fall from the belt in the region where the belt isbeing inverted. The unloading station 212 may also include a compressedair nozzle or other mechanical devices configured to assist the removalof the articles from the conveyor belt into the output bin 244. Theoutput bin 244 may be removable by an operator when it becomes full withprocessed articles.

The following section entitled Electroplating Station describes in moredetail an exemplary electroplating cell.

II. Electroplating Station

As discussed above, the electroplating station 208 of the exemplaryelectroplating system 200 may include one or more electroplating cells,such as cells 234 and 236, to form a desired partial plating ofarticles. The following describes a detailed embodiment of an exemplaryelectroplating cell that may serve as one or more cells of theelectroplating station 208 of the exemplary electroplating system 200.This exemplary electroplating cell is characterized in having a systemand method of controlling the amount of partial plating of the articles;a system and method of selectively adjusting the effective position ofthe anode; a system and method of eliminating or reducing thedemarcation line that typically forms on articles above the platingfluid surface; a system and method of providing a cathode connection tothe articles; and a system and method of improving the cathode contactof the articles. An overview of the exemplary electroplating cell isdiscussed below.

A. Overview of Electroplating Cell

FIG. 3 illustrates a side cross-sectional view of an exemplaryelectroplating cell 300 in accordance with another embodiment of theinvention. The electroplating cell 300 comprises a container 302 forsupporting a plating fluid bath. The container 302 includes lower walls304, upper walls 306, and a sparger 308, including one or morevertically-oriented thru-holes 308 a. The sparger 308 is connectedhorizontally to the lower walls 304. In this example, the upper walls306 are situated closer to each other to form a narrower upper containerportion, whereas the lower walls 304 are situated farther apart to forma wider lower container portion. Also in this example, the sparger 308traverses the lower container portion to form an upper-lower containerportion and a lower-lower container portion. The container 302 furtherincludes one or more bleed ports 310 situated between the upper walls306 and the lower walls 304. The container 302 further includes avertically-oriented inlet pipe 312 partially situated within thelower-lower container portion, and supported by a transverse member 314connected horizontally to the lower walls 304.

The electroplating cell 300 further comprises an anode electrodeconfiguration 316 including, in this example, a plurality of anodeelectrodes 316 a, 316 b, and 316 c situated in the upper containerportion between upper walls 306. The anode electrodes 316 a, 316 b, and316 c are respectively supported by respective members 318 a, 318 b, and318 c. The support members 318 a, 318 b, and 318 c, in turn, enclosewiring that electrically connect the respective anode 316 a, 316 b, and316 c to the positive terminal of a power supply. In this example, theanode electrodes 316 a and 316 c are situated near the top of therespective upper walls 306, and the anode electrode 316 bis situatedapproximately in the middle between the upper walls 306 and lower thanthe other anode electrodes 316 a and 316 c.

The electroplating cell 300 further includes one or morevertical-adjustment mechanisms 320 for adjusting the height of theplating fluid container 302. In this example, each vertical-adjustmentmechanism 320 includes a threaded container member 322 connected to theexterior of the lower walls 304 of the plating fluid container 302. Eachvertical-adjustment mechanism 320 further includes a bolt 324 threadedwith the container member 322, and having a bottom lying on asubstantially fixed member. Additionally, each vertical-adjustmentmechanism 320 includes a lock nut 326 for preventing undesired rotationof the bolt 324. The lock nut 326 is threaded with the bolt 324, andlies on top of the container member 322.

The electroplating cell 300 further includes an gas-flow system 328 fordirecting gas flow toward (positive pressure) or away from (negativepressure) the articles while they undergo an electroplating process.Examples of gases that can be used include air, nitrogen gas, argon gas,etc. The gas-flow system 328 includes a pipe 332 for routing gas flowtowards or away from a nozzle 330 that includes an opening configured todirect gas flow towards or away from the articles. As is discussed inmore detail later, the continued direction of gas flow towards or awayfrom the articles while they undergo an electroplating process preventsand/or eliminates a discoloration of the articles that typically formsabove the plating fluid bath surface.

Also illustrated in FIG. 3 is portion of an exemplary article transportsystem 350, which may be an exemplary detailed version of the transportsystem 204 of the electroplating system 200. The transport system 350comprises a frame 352 for supporting and guiding the movement of aconveyor belt 370 supporting a plurality of insert-carriers 375 which,in turn, carry respective articles 500. In this example, the frame 352comprises upper walls 354, lower walls 356, and upper cross member 358.The conveyor belt 370 is supported and guided, in particular, by thelower walls 356 of the frame 352. The frame 352 supports other elementsof the electroplating system 200 including the cathode contact system360 and the cathode contact preload system 365, which are discussed infurther detail below.

B. Controlling the Amount of Partial Plating of the Articles

The electroplating cell 300 is configured to provide a desired controlof the amount of partial plating of the articles. It achieves thisdesired control by providing a substantially stable frame 352 thatsupports articles at substantially a fixed height, avertically-adjustable plating fluid container 302, a control system forcontrolling the flow of plating fluid into the plating fluid container,and one or more bleed ports 310 embedded in the plating fluid containerto substantially stabilize the surface of the plating fluid bath.

As discussed above, the frame 352 supports and guides the movement ofthe conveyor belt 370 as it moves through the various processingstations of the electroplating system 200. A plurality of insertcarriers 375 are securely inserted into corresponding spaced-apartopenings in the conveyor belt 370. Each of the insert carriers 375support an article 500 in a substantially vertical orientation. Aportion of the article 500 below the insert carrier 375 is immersed inthe plating fluid bath supported by the container 302. It is thisportion of the article 500 that is being plated. In order to achieve thedesired control of the amount of partial plating of the articles, thevertical position of the articles should be controlled as well as theheight of the surface of the plating fluid bath.

With regard to the control of the vertical position of the articles, theframe 352 that supports the conveyor belt 370 including the insertcarriers 375 that carry the articles, is connected to a substantiallyfixed member of the electroplating system 200. In addition, the frame352 is made of relatively high strength material, such as stainlesssteel, such that the frame 352 exhibits substantially no movement in thevertical direction during the operation of the transport system 350.These characteristics of the frame 352 ensure that the articles exhibitsubstantially no movement in the vertical direction while beingtransported through the electroplating cell 300.

With regard to the control of the height of the surface of the platingfluid bath, the electroplating cell 300 includes three elements thatassist in this control. First, as previously discussed, the height ofthe plating fluid container 302 may be adjusted by thevertical-adjustment mechanism 320. This allows the proper setting of theheight of the surface of the plating fluid bath supported by thecontainer 302 by adjusting the bolt 324 and subsequently fixing thedesired position by tightening the lock nut 326. Second, the bleed ports310 allows plating fluid from the bath to bleed into a drain. The bleedports 310 improve the stability of the height of the surface of theplating fluid bath. Plating fluid from the surface of the bath alsocontinuously drains by flowing down the inclined surface of the upperwalls 306 of the container 302. Third, the flow of plating fluid intothe bath by way of the inlet pipe 312 is controlled with the use of afeedback control system, an example of which is discussed below.

FIG. 4 illustrates a block diagram of an exemplary system 400 forcontrolling the plating fluid flow into the plating fluid container 302in accordance with another embodiment of the invention. The system 400comprises a reservoir 402, a pump 406, a flow meter (FM) 408, a filter410, a controller 412, and a motor 414. The reservoir 402 holds platingfluid for use in plating articles. The pump 406 causes plating fluid toflow from the reservoir 402 to the plating fluid container 302 by way ofthe flow meter 408, filter 410, and intake pipe 312. The flow meter 408generates a signal indicative of the flow rate of the plating fluid intothe container 302. The filter 410 removes contaminants from the platingfluid. The motor 414 drives the pump 406. The controller 412 senses theflow rate of the plating fluid by receiving the signal from the flowmeter 408, and controls the motor 414 so that the desired flow rate forthe plating fluid flow is established and maintained. The controlledplating fluid flow into the container 302 and the plating fluid thatdrains out of the container 302 from the top of the electroplating cell300 and from the bleed ports 310 substantially stabilizes the height ofthe surface of the plating fluid bath.

C. Selectively Adjusting the Effective Position of the Anode

As discussed in the Background section, optimal electroplating ofdifferent articles may require different anode configurations. Forinstance, certain articles such as pins, where the plating of theirrespective side walls is most desirable, the anode electrodes should bepositioned such that the electric field lines have a generally directpath to the surface that requires plating, i.e., the side walls of thepins. Other articles, such as sockets, where the plating of theirrespective cavities is most desirable, the anode electrodes should bepositioned such that the electric field lines have a generally directpath to the surface that requires plating, i.e., the cavities of thesockets. As discussed in detail below, the exemplary anode electrodeconfiguration 316 of the electroplating system 200 allows for theeffective position of the anodes to be adjusted in order to provide thedesired plating of the articles.

FIG. 5A illustrates a side view of an exemplary anode electrodeconfiguration 316 operated in a first manner in accordance with anembodiment of the invention. In this example, the article 500 is a pin,which is being held in a substantially vertical position by the insertcarrier 375 which, in turn, is supported by the conveyor belt 370. Asdiscussed above, it is desirable to focus the plating at the lower sidewall portion of the pin 500. In such a case, it is preferable that ananode voltage is applied to only anode electrodes 316 a and 316 c, andthat no anode voltage is applied to anode electrode 316 b. This isbecause the electric field lines from the anode electrodes 316 a and 316c to the lower side wall portion of the pin 500 follow a generallydirect path. Whereas the would-be electric field lines from the anodeelectrode 316 b to the lower side wall portion of the pin 500 do notfollow a preferred path.

FIG. 5B illustrates a side view of an exemplary anode electrodeconfiguration 316 operated in a second manner in accordance with anembodiment of the invention. In this example, the article 500 is asocket including a downward-oriented cavity 502 a positioned at thelower end of the article 500. Similarly, the socket is held in asubstantially vertical position by the insert carrier 375 which, inturn, is supported by the conveyor belt 370. In this case, it isdesirable to focus the plating at the internal side wall of the cavity502 a of the pin 500. In such a case, it is preferable that an anodevoltage is applied to only anode electrode 316 b, and that no anodevoltage is applied to anode electrodes 316 a and 316 c. This is becausethe electric field lines from the anode electrode 316 b to the internalside wall portion of the cavity 502 a of the pin 500 follow a generallydirect path. Whereas the would-be electric field lines from the anodeelectrodes 316 a and 316 b to the internal side wall of the cavity 502 aof the pin 500 do not follow a preferred path.

FIG. 6 illustrates a block diagram of an exemplary anode power system600 in accordance with another embodiment of the invention. The anodepower system 600 comprises a power supply 602 including a positiveterminal and a grounded negative terminal. The positive terminal of thepower supply 602 is electrically coupled to the respective inputs ofcontrollable switching elements 602 a, 602 b, and 602 c. The switchingelements 602 a, 602 b, and 602 c include respective outputs electricallycoupled to the corresponding anode electrodes 316 a, 316 b, and 316 c ofthe anode electrode configuration 316. The anode power system 600further comprises a controller 604 having outputs respectively coupledto control inputs of the respective switching elements 602 a, 602 b, and602 c.

The controller 604 controls whether the switching elements 602 a, 602 b,and 602 c electrically connect the respective anode electrodes 316 a,316 b, and 316 c to the positive terminal of the power supply 602. Basedon inputs from an operator, the controller 604 can determine which ofthe anode electrodes 316 a, 316 b, and 316 c receives the anode voltage,and which do not. Although, in this example, three anode electrodes 316a, 316 b, and 316 c are shown, it shall be understood that the anodeelectrode configuration 316 may include any number of electrodes.Although not shown, the anode power system 600 may include one or morevoltage regulators to independently regulate (and/or in common) theanode voltages at the respective anode electrodes 316 a, 316 b, and 316c. Alternatively, the anode power system 600 may have independent powersupplies for the respective anode electrodes 316 a, 316 b, and 316 c.

D. Eliminating or Reducing the Demarcation Line on Articles

As discussed in the Background section, during the partial plating of anarticle, a ring-shaped discoloration, also referred to as a demarcationline, is often formed around the article near the surface of the platingfluid bath. It has been previously theorized by others that thedemarcation line was formed at the surface of the plating fluid bath.Through various experiments, the inventors have discovered that thedemarcation line actually forms on the article a relatively shortdistance above the surface of the plating fluid bath. The inventorstheorized that the demarcation line is formed by ejection of the platingfluid and subsequent impingement of the vapors onto the article. Basedon this theory, the inventors have devised a method of preventing orreducing the occurrence of the formation of the demarcation line onarticles.

With reference again to FIG. 3, the electroplating cell 300 includes angas-flow system 328 for directing gas flow toward or away from thearticles while they undergo the electroplating process. As discussedabove, the gas-flow system 328 includes a pipe 332 for routing gas flowtowards or away from a nozzle 330 that includes an opening configured todirect gas towards or pull gas from the articles. Examples of gases thatcan be used include air, nitrogen gas, argon gas, etc. The continued gasflow towards or away from the articles while they undergo anelectroplating process prevents and/or reduces the impingement of thevapors on the articles. Thus, with the use of the gas-flow system 328,the discoloration of the articles may be prevented or substantiallyreduced.

E. Providing a Cathode Connection to the Articles

FIG. 7A illustrates a side view of an exemplary cathode contact system360 in accordance with another embodiment of the invention. The cathodecontact system 360 is configured to provide a cathode contact to thearticles while preventing contamination of the electroplating cell 300.The cathode contact system 360 comprises a point of electrical cathodecontact 361, a resilient device 326 including a brush 363 situated atits lower end, an exterior cathode contact wheel 364, an interiorcathode contact wheel 367, a drive shaft 366, and a pair of bearings 365for the wheels 364 and 367.

The point of contact 361, which in this example is a bolt threaded intoa housing and secured by a lock nut, is electrically coupled to theresilient device 362 including the brush 363. The resilient device 362is resilient generally in the vertical direction and absorbs upwardvertical energy produced by the rotating exterior cathode contact wheel364. The brush 363 makes electrical contact to the perimeter of theexterior cathode contact wheel 364. The drive shaft 366 is rotationallycoupled and makes electrical contact to the exterior cathode contactwheel 364 and the interior cathode contact wheel 367. The bearings 365secure the wheels 364 and 367 to fixed members, such as the frame 352 ofthe transportation system 350, while allowing the wheels to rotate. Theinterior cathode contact wheel 367 is rotationally and electricallycoupled to the conveyor belt 370. The conveyor belt 370, in turn, iselectrically coupled to the articles 500 by way of their respectiveinsert carriers 375.

Thus, with the exemplary cathode contact system 360 of the invention, acathode voltage potential is applied to the articles by way of the pointof contact 361, resilient device 362 including its brush 363, theexterior cathode contact wheel 364, the drive shaft 366, the interiorcathode contact wheel 367, the conveyor belt 370, and the insertcarriers 375. An advantage of the cathode contact system 360 is that thebrush 363 makes electrical contact to the exterior cathode contact wheel364 at a location outside of the electroplating cell 300. In thismanner, particles of the brush 363 that flake off as it makes contactwith the moving exterior cathode contact wheel 364 does not contaminatethe plating fluid bath. Thus, a cathode contact may be provided tomoving articles in a contaminant free manner because a fixed member(e.g., brush 363) makes contact with a moving member (e.g., wheel 364)outside of the electroplating cell 300.

FIG. 7B illustrates a side view of another exemplary cathode contactsystem 380 in accordance with another embodiment of the invention. Thecathode contact system 380 comprises an electrical conduit 382 and abrush 384. The electrical conduit 382 may be routed from outside of theelectroplating cell where it receives the cathode potential, through anopening within a wall of the transport system frame 352, and downwardstowards the conveyor belt 370. The brush 384, electrically connected tothe lower end of the electrical conduit 382, makes electrical contact tothe conveyor belt 370. Thus, a cathode potential is applied to thearticle 500 by way of the electrical conduit 382, brush 384, conveyorbelt 370, and insert carrier 375. The contact of the brush 384 to theconveyor belt 370 may be configured such that there is no or minimalcontamination of the plating fluid by particles emanating from the brush384 as a result of its frictional contact with the moving conveyor belt370.

F. Improving the Cathode Contact to the Articles

FIG. 8 illustrates a side view of an exemplary cathode contact preloadsystem 390 in accordance with another embodiment of the invention. Thecathode contact preload system 390 applies a continuous downward forceon the articles 500 to ensure that they make good electrical andphysical contact with their corresponding insert carriers 375 while thearticles are being plated. In particular, the cathode contact preloadsystem 390 comprises an endless belt 392 rotationally supported by apair of idle wheels 394 (only one shown). The cathode contact preloadsystem 390 further comprises a drive belt 396 rotationally coupling oneof the idle wheels 394 to a drive wheel 377 rotationally coupled to theconveyor belt 370. In this manner, the endless belt 392 moves atsubstantially the same speed as the conveyor belt 370 that transportsthe articles 500 through the various processing stations.

FIG. 9A illustrates a side view of the exemplary endless belt 392 of thecathode contact preload mechanism 390 in contact with a pair of articles500 in accordance with another embodiment of the invention. The endlessbelt 392, being made of a resilient material (e.g., rubber), makescontact to the top regions the articles 500. The resilient nature of thebelt 392 results in the belt 392 exerting a substantially downward forceF against the tops of the articles 500. This downward force F forces thearticles against the insert carriers 375, thereby providing a positiveelectrical and physical contact of the articles 500 to the insertcarriers 375 as the articles 500 are transported through the variousprocessing stations of the electroplating system 200. As discussedabove, the conveyor belt 370 as well as the insert carriers 375 areelectrically coupled to the cathode terminal of a power supply. Thus,the downward force F exerted by the belt 392 against the articles 500allows a consistently good cathode contact to be made to the articleswhile they undergo the electroplating process.

As an alternative embodiment, the endless belt 392 may be made of anelectrically conductive material (e.g., a conductive rubber or a metalband). In such a case, the cathode contact to the articles 500 may bemade by way of the endless belt 392. Also, in such a case, the conveyorbelt 370 and the insert carrier 375 need not be made of an electricallyconductive material. Again, this is because the endless belt 392provides the cathode contact to the articles 500. The cathode contact tothe electrically-conductive, conveyor belt 392 may be made by a slidingcontact member that slides against the moving belt 392 or a rotatingcontact member that rotates against the moving belt 392.

FIG. 9B illustrates a side view of another exemplary endless belt 398 inaccordance with another embodiment of the invention. In this example,the endless belt 398 is made of an electrically conductive material(e.g., a metal). In addition, the endless belt 398 includes a pluralityof spaced-apart, spring-loaded fingers 399 configured to register withthe top end of the articles 500. Accordingly, the cathode contact to thearticles 500 may be made by way of the endless belt 398 and therespective spring-loaded fingers 399.

FIG. 10 illustrates a block diagram of an exemplary synchronizationsystem 1000 to synchronize the speed of the article transport conveyorbelt 370 with the cathode contact conveyor belt 392 (or belt 398) inaccordance with another embodiment of the invention. The synchronizationsystem 1000 comprises the drive motor 373 for the article transportconveyor belt 370, a controller 1002, and a variable-speed or DC servodrive motor 1004 for the cathode contact conveyor belt 392. The drivemotor 373 for the article transport conveyor belt 370 may include themotor portion 373 a as well as a revolution per minute (RPM) encoder 373b which generates a signal indicative of the speed of the motor portion373 a. It shall be understood that the RPM encoder 373 b may beintegrated with the motor portion 373 a, or may be separate there from.It shall be understood that the belt 370 may be replaced with othertypes of conveyable structures, such as a chain or cable.

The controller 1002 receives the signal generated by the RPM encoder 373b. Based on this signal, the controller 1002 generates a speed controlsignal for the cathode contact motor 1004. Since the cathode contactmotor 1004 and cathode contact conveyor belt 392 may be configured tohave different speed control characteristics, the controller 1002performs the appropriate calculations to generate a speed control signalfor the cathode contact motor 1004 such that the movement of the cathodecontact conveyor belt 392 is substantially in synchronous with themovement of the article transport conveyor belt 370. This ensures thatthe preload cathode contact to the articles by the article transportconveyor belt 370 is substantially fixed as the articles are transportedthrough the various cells of the electroplating system 200.

III. Transport System

A. First Embodiment

With reference again to FIGS. 1, 8 and 9, the transportation system 204comprises an endless, electrically-conductive conveyor belt 370 that isrotationally supported by a drive wheel 371 and an idle wheel 372. Thedrive wheel 371 is rotationally coupled to a drive motor 373 for movingthe conveyor belt 370. The transportation system 204 may further includea tension wheel 374 to keep the conveyor belt 370 desirably taut duringtransportation of the articles 500. The endless belt 370 furthercomprises a plurality of spaced-apart thru-holes 370 a configured torespectively receive insert carriers 375 that hold articles. The insertcarriers 375 snap into the respective openings 370 a such that insertcarriers 375 are secured to the conveyor belt 370.

FIG. 11 illustrates a side view of a portion of the exemplary articletransport system 204 in accordance with another embodiment of theinvention. As shown, the endless belt 370 includes an overlap region 372where two portions of the belt overlap and are attached together to makethe belt endless. In the overlap region 372, the thru-holes 370 a of theoverlapping portions of the belt 370 register with each other, i.e.,they are substantially coaxial. The overlapping portions of the belt 370may be attached to each other by epoxy, mechanical or others means.Also, in the overlap region 372, the insert carriers 375 are insertedthrough respective registered pairs of openings 370 a.

The conveyor belt 370 is made out of relatively high tensile strengthmaterial so as to prevent unwanted flexing in the region where thearticles 500 are carried. This further ensures that the verticalposition of the articles 500 is substantially stable to control theamount of partial plating of the articles. Furthermore, the position ofthe conveyor belt 370 is such that it does not contact the platingsolution. This reduces the amount of maintenance (e.g., cleaning and/orreplacement) required on the conveyor belt 370. It shall be understoodthat the belt 370 may be replaced with other types of conveyablestructures, such as a chain or cable.

FIG. 12A illustrates a side view of an exemplary carrier 375 asupporting an article 500 a in accordance with another embodiment of theinvention. An advantage of the article transport system 204 of theelectroplating system 200 is that it is relatively easy to configure thesystem to handle different types of articles. In particular, insertcarriers may be designed to hold different types of articles while stillbeing able to be properly attached to the conveyor belt 370. Morespecifically, the interior configurations of various types of insertcarriers may be designed to properly support different articles. While,the outside configuration of such various types of insert carriers maybe kept substantially the same so that they can be properly attached tothe conveyor belt 370.

In this example, the interior configuration of the insert carrier 375 ais designed to support an elongated cylindrical-shaped article 500 a(e.g., a pin) that includes a ridged portion that makes contact with theinterior of the insert carrier 375 a. The upper interior walls of theinsert carrier 375 a is angled inward to guide the article 500 a whileit is being fully inserted into the insert carrier 375 a. The externalconfiguration of the insert carrier 375 a is designed to friction fitinto the thru-holes 370 a of the conveyor belt 370. As discussed below,if a different type article is to be plated, the interior configurationof the insert carrier may be designed differently to properlyaccommodate the article, while the exterior configuration be kept thesame so that it properly interfaces with the conveyor belt 370.

FIG. 12B illustrates a side view of another exemplary carrier 375 bsupporting another article 500 b in accordance with another embodimentof the invention. In this example, the interior configuration of theinsert carrier 375 b is designed to support an elongatedcylindrical-shaped article 500 b that includes a cylindrical flangestructure that makes contact with the interior of the insert carrier 375b. Similar to insert carrier 375 a, the upper interior walls of theinsert carrier 375 b is angled inward to guide the article 500 b whileit is being fully inserted into the insert carrier 375 b. The externalconfiguration of the insert carrier 375 b is substantially the same asthat of insert carrier 375 a so that it can be friction fit into thethru-holes 370 a of the conveyor belt 370.

Thus, the plating of different articles is facilitated with thecustomizable insert carriers 375. The conveyor belt 370 may be populatedwith the first-type insert carriers 375 a to support first-type articles500 a while they undergo the various processes performed by theelectroplating system 200. Once the processes are completed on thefirst-type articles 500 a, the first-type insert carriers 375 a areremoved from the conveyor belt 370, and the conveyor belt 370 is thenpopulated with the second-type insert carriers 375 b to supportsecond-type articles 500 b while they undergo the various processesperformed by the electroplating system 200.

B. Second Embodiment

FIGS. 13A-D illustrate front, side, top and open views of anotherexemplary article transport system 1300 in accordance with anotherembodiment of the invention. The article transport system 1300 comprisesa conveyor belt 1302 and a multi-article carrier 1304 supported by theconveyor belt 1302. The multi-article carrier 1304 comprises a base 1306and a cover 1308 connected to the base 1306 via a hinge 1310. The bottomof the base 1306 includes a plurality of openings 1312 to receive therethru the articles 500. The openings 1312 register with correspondingopenings of the conveyor belt 1302 such that the articles 500 extendthere thru below the conveyor belt 1302 and into the electroplating cell1350. The openings 1312 may be configured into a single row, into anarray consisting of a plurality of rows, or into any other pattern.

The cover 1308 of the multi-article carrier 1304 comprises a cathodecontact port 1314 to receive the cathode potential. The cover 1308further includes an internal electrical conduit 1316 which iselectrically coupled to the cathode contact port 1314 and routes thecathode potential towards the articles 500. The cover 1308 furthercomprises a plurality of spring-loaded cathode fingers 1318 that makepressured electrical contact to the respective articles 500. Thespring-loaded cathode fingers 1318 are electrically connected to theelectrical conduit 1316. Thus, the articles 500 receive the cathodepotential by way of the cathode contact port 1314, internal electricalconduit 1316, and respective spring-loaded cathode fingers 1318.

In operation, at a loading station, an empty carrier 1304 has its cover1308 initially in an open position as shown in FIG. 13D. The articles500 are then inserted into the holes 1312 of base 1306 of the emptycarrier 1304 such that articles 500 extend below the conveyor belt 1302.Once the articles 500 are properly inserted into the holes 1312 and aresupported by the carrier 1304 and conveyor belt 1302 in a substantiallyvertical orientation, the cover 1308 is then closed as shown in FIG.13A. As discussed above, in the closed position, the spring-loadedcathode fingers 1318 make pressured electrical contact to the respectivearticles 500. It shall be understood that the conveyor belt 1302 may besome other type of movable supporting structure, such as a chain orcable. In addition, the conveyor belt 1302 can be an electricalconductor (e.g., a metal or conductive rubber) and/or a non-electricalconductor.

While the invention has been described in connection with variousembodiments, it will be understood that the invention is capable offurther modifications. This application is intended to cover anyvariations, uses or adaptation of the invention following, in general,the principles of the invention, and including such departures from thepresent disclosure as come within the known and customary practicewithin the art to which the invention pertains.

1. An electroplating system, comprising: a container adapted to supporta plating fluid bath; an anode electrode positioned within saidcontainer and adapted to make contact with said plating fluid bath; asupport structure adapted to support an article in a manner that only aportion of said article is immersed in said plating fluid bath; and agas flow system adapted to cause gas flow proximate an interface of saidarticle to said plating fluid bath.
 2. The electroplating system ofclaim 1, wherein said gas flow system is adapted to direct gas flowtowards said interface of said article to said plating fluid bath. 3.The electroplating system of claim 1, wherein said gas flow system isadapted to direct gas flow away from said interface of said article tosaid plating fluid bath.
 4. The electroplating system of claim 1,wherein said gas flow system comprises: a pipe fluidly coupled to apressurized gas source; and a nozzle fluidly coupled to said pipe. 5.The electroplating system of claim 1, wherein said gas comprises any oneor more of the following air, nitrogen gas, and/or argon gas.
 6. Amethod of electroplating an article, comprising: forming a plating fluidbath; immersing only a portion of an article in said plating fluid bath;generating a plating current through said plating fluid bath and saidarticle; producing gas flow proximate an interface of said article tosaid plating fluid bath while said plating current is flowing throughsaid plating fluid bath and said article.
 7. The method of claim 6,wherein said gas flow is directed towards said interface of said articleto said plating fluid bath.
 8. The method of claim 6, wherein said gasflow is directed away from said interface of said article to saidplating fluid bath.
 9. The method of claim 6, wherein said gas comprisesany one or more of the following air, nitrogen gas, and/or argon gas.10. An electroplating system, comprising: a pre-processing stationincluding one or more pre-processing cells; an electroplating stationincluding one or more electroplating cells; a post-processing stationincluding one or more post-processing cells; and a transport systemadapted to transport articles horizontally through said pre-processingstation, said electroplating station, and said post-processing station;wherein at least one of said electroplating cell comprises: a containeradapted to support a plating fluid bath; an anode electrode positionedwithin said container and adapted to make contact with said platingfluid bath; wherein said transport system is adapted to support saidarticles in a manner that only selected portions of said articles areimmersed in said plating fluid bath; and a gas flow system adapted tocause gas flow proximate respective interfaces of said articles to saidplating fluid bath.
 11. The electroplating system of claim 10, whereinsaid gas flow system is adapted to direct gas flow towards saidrespective interfaces of said articles to said plating fluid bath. 12.The electroplating system of claim 10, wherein said gas flow system isadapted to direct gas flow away from said respective interfaces of saidarticles to said plating fluid bath.
 13. The electroplating system ofclaim 10, wherein said gas flow system comprises: a pipe fluidly coupledto a pressurized gas source; and a nozzle fluidly coupled to said pipe.14. The electroplating system of claim 10, wherein said gas comprisesany one or more of the following air, nitrogen gas, and/or argon gas.